<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .parent {
            display: flex;
        }

        .item {
            width: 100px;
            height: 100px;
            border: 2px solid palevioletred;
            font-size: 30px;
            text-align: center;
        }
    </style>
    <script src="./demo.js"></script>
</head>

<body>
    <br>
    <br>
    <form action="#" onsubmit="return false;">
        <label for=""><input type="radio" name="option" value="row" data-attr="flexDirection">row</label>
        <label for=""><input type="radio" name="option" value="row-reverse" data-attr="flexDirection">row-reverse</label>
        <label for=""><input type="radio" name="option" value="column" data-attr="flexDirection">column</label>
        <label for=""><input type="radio" name="option" value="column-reverse" data-attr="flexDirection">column-reverse</label>
    </form>
    <br>
    <div class="parent">
        <div class="item">1</div>
        <div class="item">2</div>
        <div class="item">3</div>
        <div class="item">4</div>
        <div class="item">5</div>
        <div class="item">6</div>
    </div>
</body>

</html>